Amazing capture. :O Ducks will eat anything they can catch (so will frogs) - you were in the right place at the right time for this one. No.3 is priceless. If LIFE Magazine were still publishing, this would be perfect for their last page feature photo.

I end up watching ducks a lot -- just because they always seem to be there, and I've never seen this, or anything close. I always assumed that they were eating aquatic vegetation.

I have some shots (not very good ones) of an American Coot who had somehow apparently caught a rather large Crappie. There was no way the coot would be able to eat it, and it spit it out. The Crappie swam off and is probably still telling the story of how this crazy Coot tried to kill him. :-)

I guess that when you watch animals enough, you'll probably eventually see all kinds of unlikely things. . .
The really cool part is when you actually have your camera ready and are able to get some shots -- and they turn out to be as good as you had hoped they'd be.